On its way to becoming the fastest-selling Android smartphone, the Galaxy S4 has been sold twice as many times as the HTC One in their first few weeks on the market.

Samsung announced this week that it has sold 10 million Galaxy S4 phones. Currently in either black or white, the phone manufacturer plans to sell the smartphone in more colors, such as blue, red, purple and brown, later this year. An HTC executive told the Wall Street Journal its device had been purchased 5 million times, but that production remains behind schedule because of parts shortages.

The One had been expected to hit the market ahead of the Galaxy S4. Instead, the phones came out at nearly the same time because of delays by HTC suppliers.

Reviewers generally credited the One with having top-of-the-line hardware and the S4 with containing innovative software features. Both companies have aggressively marketed their phones, but Samsung’s continued dominance with its Galaxy line has led to turmoil inside HTC. Multiple HTC executives recently left the company. And the HTC First, the phone that was used to launch Facebook’s Home feature last month, has been a flop.

Samsung also said last week it would soon sell a version of its phone with the default Android software installed rather than a version of Android customized by Samsung. An HTC developer said on Twitter last week that HTC should be expected to release a One with an un-customized version of Android too.

Some users may delay purchases of the S4 to get the new version or one of the other colors, but the influx of Verizon customers could keep sales steady.

The previous fastest-selling phone, the Galaxy S III, needed almost two months to reach 10 million units sold, Samsung said.